1. Field of the Invention
In general, the present invention relates to auxiliary handles that are used to assist a person in rapidly turning a rounded knob in a more ergonomically efficient manner. More particularly, the present invention relates to auxiliary handles that form the crank structures when attached to a rounded knob.
2. Description of the Prior Art
Knobs are used on many different mechanisms as the interface through which a person can manually turn some adjustable element on that mechanism. There are many different types of knobs, wherein the structure of the knob usually is dictated by its use. Rounded knobs are often used on mechanisms that require only a small degree of torque. Rounded knobs are directly grasped by a person""s hand, wherein the fingers on the hand engage the surface of the rounded knob through friction. As such, only a small amount of torque can be transferred to the rounded knob by a person""s hand. For example, many doors have round door knobs. The locks on doors require only a small degree of torque in order to turn. Once turning, door knobs need only be rotated a short distance in order to open the door""s locking mechanism. For such situations where a small degree of torque must be applied for just a short rotated distance, round knobs are appropriate.
Rounded knobs, however, are not appropriate for all applications. If an application requires a greater torque than can be applied by the average wrist, rounded knobs do not work. Rather, in such situations, lever knobs are commonly used. Lever knobs have long handles that provide leverage and increase the amount of torque capable of being applied by a person""s hand. However, lever knobs are only practical in applications where the lever knob is used to create a short rotational movement.
In applications where a substantial amount of torque must be applied for numerous rotations, crank knobs are commonly used. Crank knobs provide torque and enable a person to turn a knob hub much more rapidly than would be possible with a rounded knob.
In the prior art, there exist many different devices that are used to convert a rounded knob into either a lever knob or a crank knob. For example, U.S. Pat. No. 4,285,536 to McCoy, entitled, Universal Lever Handle Attachment For A Door Knob, shows a lever attachment for a rounded door knob. This enables older or weaker people to better grasp and turn a simple door knob. A problem associated with such prior art devices is that they are attached to a single door knob with tools. Thus, they are difficult to install and they are not practical to move from door to door.
U.S. Pat. No. 5,272,953 to Koch, entitled String Winder Tool For Musical Instrument,shows a crank attachment that can be rapidly moved from one knob to another. However, the device only works with the flat tuning knobs of stringed instruments and cannot be used on more common rounded head knobs that are used on equipment other than musical instruments.
A need therefore exists for an auxiliary attachment device for a rounded knob that can rapidly engage a rounded knob, turn a rounded knob and again be detached from the rounded knob so that it can be used on a different knob. This need is provided by the present invention as described and claimed below.
The present invention is a device and method for engaging a rounded knob so that the knob can be turned in a more rapid and ergonomically efficient manner. The claimed invention includes an auxiliary handle device. The auxiliary handle device includes a hub and a handle that extends radially away from the hub. The hub is configured to pass over the exterior of the rounded knob. Once the hub envelopes the rounded knob, the handle is rotated. As the handle is rotated, an interference fit is created between the interior of the hub and the knob. The interference fit transfers the rotational energy from the handle to the rounded knob, thereby rotating the rounded knob. The handle can be formed either as a straight handle or with a crank extension, thereby enabling a person to rapidly engage and turn a rounded knob with a mechanical advantage in applied torque.